Plastic polyvinyl acetal compositions



Patented Oct. 10, 194 4 POLYVINYL AGE COMPOSITIONS UNIT D STATES v PATENT ms'ric OFFICE am 1:. Nason, St. Louis, Mo. norm. townlento. Chemical Company. porationpt Delaware lso Drawing. Application Serial No. 281,8

8t. Intrigue.. a cor-.

June as, rose, 1':

1; Claims. (cl. zen-as) The present invention relates to polyvinyl acetal resins and to softening and plasticizing substances therefor. This invention is directed particularly to polyvinyl acetal resinous compositions plasticized with alkyl diphenyls in con- Junction with other plasticizers and more particularly in conjunction with phthalate esters.

It is an object of the present'invention to provide a plasticizer composition for polyvinyl acetal resins which imparts to plastic compositions embodying such resins certain especially desirable characteristics such as stability to light and heat, flexibility without softness or tackiness. Further objects and advantages of my invention will be apparent from the description hereinafter.

In United States Patent No. 2,115,524, granted in Carroll A. Hochwaltand Nicholas N. T. Samaras, there is disclosed the use of various alkyl diphenyis as plasticizers for vinyl resins, acrylic acid resins, styrene resins and thelike;

and particularlyior thermosetting phenol-alde-' hyde resins when used in small proportions. This present application is directed to compositions embodying polyvinyl acetal resins in admixture ly enhanced characteristics have been obtained,

which compositions are particularly suitable ior use as interlayers in laminated or safety glass, as

is pointed out more completely hereinaiter.

Polyvinyl acetal resins are generally designated as resins resultins. irom condensation of an aldehyde such as ior example formaldehyde. acetaldehyde, propionaldehyde or, butyraldehyde with a polyvinyl alcohol or partially esterified poly. vinyl alcohol. In general, they are produced by partial orcomplete hydrolysis of a vinyl ester polymer such as polyvinyl acetate and subsequent condensation of such hydrolysed polymer withan aldehyde. Such resins are described. ior example, in United States Patent No. 2,086,092, dated March 31, 1936. Commercial polyvinyl acetal resins are known to the industry under such trade names as Formvar," "Alvar," and These resins are especially dimcult to plasticize with any outstanding degree of success by means or the plasticizers commonly used for cellulose esters and ethers such as dibutyl phthalatacamphor, tricresyl phosphate and the like. Inasmuch as these polyvinyl acetal resins are 01' outstanding toughness and are especially desirable as safety glass interlayers, extensive in- Q vestigations have been in progress to discover plasticizers which would overcome the inherent brittleness of the resins and provide plastic compositions which could be used for such purposes.

Many plasticizers atter -incorporation with polyvinyl acetal resins and formation or a-fllm from the resulting composition, provide films of the requisite degree of flexibility but such films are tacky and soft, lacking firmness or hardness,

and cannot be manipulated easily in. sheet form. Other plasticizers cannot beincorporated in suificient proportions, that is, they are not retained by the composition in suiiicient proportion to have any substantial 'eilect on the flexibility oi the resulting film. Dibutyl phthalateds an example ot a plasticizer which when present in any substantial proportions in polyvinyl acetal films imparts tackiness and soitness to the films when presentin sufiicient proportion to have a substantial efiect on flexibility. The use 0! many other plasticizers is precluded because 01. their instability to light and heat, their volatility and their high cost.

. resins, and'that the films formed from such com- .1

" ".tion by light and heat and are clear, transparent;

It has now been discovered that mixtures oi alkylated diphenyls and other plasticizers such for example as alkyl phthalate ester plasticizers can be used as plasticizers for polyvinyl acetal positions are remarkably resistant to discolora- "colorless and oi excellent appearance, and are free from the tackiness exhibited by P lyvinyl acetal resin films having the same degree oi flexibility that are plasticized with dibutyl phthalate. The polyvinyl acetal resin films piastized with a mixture of dibutyl phthalate and an ethylated diphenyl are especially flexible at low temperatures, which is an important characteristic when. their use as interlayers for safety glass is contemplated,

and this fiexibility is achieved without any appreciable degree of tackiness being imparted to the. film. The mixtures oivalkylated diphenyls with other plasticilers, contrary to expectations,

impart characteristics to polyvinyl acetal resin films which were not predictable irom the respective actions of the individual plasticizers in such films. One compensate! the plasticizer mixture not only complements the action of theother component but imparts, to the resulting compositicn, characteristics not possessed to any substantial degree by either component.

Alkyiated diphenyls" as the term is used here.- inaiter, is to be understood to designate single substantially pure alkyl diphenyls such as ethyl diphenyl, propyl diphenyl, butyl diphenyl, amyl diphenyl, hexyl diphenyl and higher homologues, as well'as the various isomers thereof and mixtures of such isomers and the corresponding dialkyl and polyalkyl diphenyls and mixtures thereof, and mixtures of alkylated diphenyls of the same or varying degrees of alkylation. The alkyl diphenyls may be normaly liquid or solid crystalline or waxy bodies. Certain pure alkyl diphenyls have been heretofore prepared by various methods including certain indirect methods of synthesis. Especialy useful for the purposes of this invention are the normaly liquid products obtained by direct alyklation of diphenyl with olefins such as ethylene. propylene, butylene, amylene or the corresponding alkyl halides or the corresponding alcohols. v By the term alkyl phthalateesters as used herein are designated the neutral alkyl esters of phthalic acid such as dimethyl phthalate, diethyl phthalate, dipropyl phthalate. diisopropyl phthalate, normal-dibutyl phthalate. and. the various ethylated diphenyl were liquid at room temperature.

Example 2.'-To 100 grams of the fButvar resin used in Example 1 were added 35 parts of a liquid fraction of ethylated diphenyl having a boiling range of 127 to 167 C. at a pressure of 3 mm. of mercury whose preparation was de-' scribed in Example 1 and 25 parts of di-n-butyl phthalate. incorporate the ingredients and then formed into a sheet of approximately the same thickness as the film of Example 1.

The resulting film was characterized by the .same exceptional properties to substantially the same degree as those of the film of Example 1.

Example 3.A film was prepared by the method described in Examples 1 and 2, using a isomeric dibutyl phthalates, as well as higher homologues and more complex alkyl esters such as glycol phthallates which may be obtained by esterification of phthalic acid with the corre-.

sponding monohydric alcohols or polyhydric glyv cols, or glycol ethers and esters, or by reaction of a phthalic acid salt with the corresponding alkyl chloride.

Typical compositions of my invention are illustrated in the examples which follow and the advantages and characteristics of such compositions are described both in the examples and are -manifest in the results of tests hereinafter set forth.

Example 1.To 100 grams of acommercial Butvar resin, the condensationproduct of butyraldehvde and a partialy hydrolyzed polymer or vinyl acetate, comprising 16 to 20 hy-' droml calculated as polyvinyl alcohol, 2% or less of aectate and the balance acetal, were added 35 grams of a fraction of ethylated diphenyl having a boiling range 0! 105 to 127 C. at 3 mm.

pressure and grams of di-n-butyllphthalate. The mixture-was heated in a glass beaker at 110 'C. and subsequently pressed into films of a thickness'of about 0.03 inch. The resulting film was clear, transparent, colorless and showed very little discoloration when subjected to heating in an oven at 105 C.'for 120 hours. The film was'not tacky and had 'a desirable firmness or hardness acompanied by good flexibility.

The ethylated dlphenyl fraction was prepared by passing ethylene slowly into *dlphenyl containing approximately 3 to 5% anhydrous aluminum chloride (based on the weight of diphenyl) until approximately 3 molecular proportions of ethylene to 1 molecular proportion of diphenyl had been absorbed. The catalyst layer was??- rated and the product was fractionated der vacuum. Two fractions were collected, one having a boiling range from 105to 127 C. at 3 mm. pressure, which was used in this example, and the other having a boiling range from 127 to 167 C. at 3 mm. pressure, which was used in example 2, hereinafter shown. Both these fractions of composition consisting of parts by weight of posite fraction of the two fractions separated in Example 1.

This film was similar to those of, Examples 1 and 2 but was somewhat more resistant to discoloration by heat, the color being substantially unafifected by exposure at C. for hours. Example 4.-A film was prepared by the method described in Example 1, using a composition consisting of 100 parts by weight of Butvar" resin, 25 parts by weight of di-n-butyl phthalate and 35 parts by weight of a liquid butytlated diphenyl consisting of a fraction having a boiling range irom'12'1 to 210 C. at a pressure of 3 mm. obtained by passing butylene into molten diphenyl in the presence of 3 to 5 per cent of anhydrous aluminum chloride (based on the weight of diphenyl) until approximately 0.84 molecular proportion of butylene had been absorbed per molecular proportion of diphenyl. The butylated dipheny'i was a liquid at room temperature.

This film was slightly less resistant to discoloration by .heatthan anyof those of Examples 1, 2 and 3, but its resistance was good. The slightdarkening observed after exposure for 24 hours at 105 C. was not substantial.

Example 5 .A film was prepared by the method described in Example 1, using a composition consisting of 100 parts of Butvar resin, 25 parts of di-n-butyl phthalate and 35 parts of a liquid propylated diphenyl having a boiling range of 122 to C. at a pressure of 3 mm.

The propylated diphenyl fraction was obtained by reaction of molten diphenyl containing 3 to 5 per cent. of its weight of anhydrous aluminum chloride with propylene until approximately 3 The mixture was warmed to 110 to I several hours exposure at Example 6.-A film was prepared as in Exampie by substituting a fraction of the propylated diphenyl having a boiling range of 126 to ing range used in Example 5.

In all respects this film was substantially identical with that of Example 5. Its resistance to 145 C. at 3 mm. for the fraction of wider boildiscoloration by heatwas similar to' that made I in the foregoing. examples with .ethylated diphenyl fraction and very slightly less stable to discoloration after 120 hours at 105 C. than the film of Example 5.

Comparison film-Forcoinparison tests, a'

film was prepared by incorporating 00 parts of di-n-butyl phthalate with 100 parts of "Butvar" resin. The film was tacky, had satisfactory fiexibility, but was not firm or hard and could not be easily handled in sheet form. The fllm discolored after 48 hours exposure to a temperature of 70 C. Its color darkened appreciably after Flexibility tests The films prepared hereinabove, all having a thickness of from 0.02 to 0.03 inch, were sub- Jected to bending or folding at a temperature of phosphate diethyl adipate,

through 180 C. and backtov the original position. V

Film Thicknw, Bendsior B'endslor inches first break final break 0.027 100 280 0.0330 120 200 0.0310 54 88 0.0276 81 101 00207 as 108 0.032 14 to 0.020 78 a 110 Typical polyvinyl acetal resins for which the 'alkylated diphenyl plasticizers of the present invention are suitable have been specified hereinbefore. Other plasticizers with which the alkylated diphenyls are contemplated for use include in general, alkyl phthalate esters, alkyl and aryl esters such as tributyl phosphate, triphenyl phosphate and tricresyl phosphate, fat- 7 ty acid esters of mono and polyhydric alcohols as for example butyl laurate. diethylene glycol are to used will be dependent to a great extent upon the flexibility desired in the resulting film, and upon the solubility characteristic of the particular acetal resin employed. In my examples I have shown the most desirable ranges of the particular mixed plasticizers for use in V the production of films from "Butvar resin for use as safety glass interlayers. These optimum proportions are approximately 35 to 40 parts of ethylated or similar allwlated diphenyl, 20 to 25' parts of dibutyl phthalate and 100 parts of Butvar." With other polyvinyl acetal resins a slightly different ratio of the components might be preferred. Thus, in the case of Formvar" comprising substantially 82 percent acetal, 8%

hydroxyl groups calculated aspolyvinyl alcohol and 10% acetate, a reduced amount of alkylated diphenyl is employed and diethyl phthalate is preferably substituted for dibutyl phthalate.

7 Other components may be added to the plastic compositions of this invention in the usual manner to provide different eflects, for example, stabilizers for the resin such as amines, coloring ingredients, filling ingredients, opacifying agents, and the like.

, Inasmuch as the foregoing description comprises preferred embodiments,'it is to be understood that my invention is not limited thereto and that variations and modifications may be made in known manner without depar ing substantially from the invention which is defined in dibutyrate, triethylene glycol dih'exoate. esters of theappended claims.

What I claim is: l. A plastic composition of matter characterized by substantial lack of tackiness and possessing resistance to the action of light and heat consisting essentially of a polyvinyl acetal resin and comprising an alkylated diphenyl as one component of a mixed plasticizer. the other component of which normally imparts tackiness to the polyvinyl acetal resin.

2. A plastic composition of matter characterized by substantial lack of tackiness and possessing resistance to the action of light and heat and being flexible at low temperatures in film form consisting essentially of a polyvinyl acetal resin andcomprising a'mixture of an alkyiated diphenyl and an alkyl phthalate ester as a plasticizer therefor. I v Y a 3. A plastic composition of matter characterized by substantial lack of tackiness and possessing resistance to the action of light and heat and being flexible at low temperatures in film form consisting essentially of a polyvinyl acetal resin and comprising as a plasticizer therefor a mixture of from 35 to 40 parts of an alkylated diphenyl and from 20 to 25 parts of an alkyl phthalate ester to each parts of the resin.

4. A composition as definedin claim 2 in which the alkylated diphenyl is an ethylated diphenyl obtained by ,direct ethylation of diphenyl with lyst A l 5. A composition as defined in claim 2 in which the alkylated diphenyl i a propylated diphenyl and being flexible at low temperatures in film.

form, consisting esentially of a polyvinyl butylal ethylene in the presence of a Friedel-Crafts cata-- resin and comprising as a plasticizer therefor a mixture of from 35 to 40 parts of an alkylated diphenyl, the alkyl groups of which have less than six carbon atoms and from to parts of dibutyl phthalate to each 100 parts of the resin.

8. A plastic composition of matter characterized by substantial lack of tackiness and possessing resistance to the action of light and heat and being flexible at low temperatures in film form, consisting essentially of a polyvinyl (ormal resin and comprising as a plasticizer therefor a mixture of from to 40 parts of an alkylated diphenyl, the alkyl groups of which have less than six carbon atoms, and from 20 to 26 parts of diethyl phthalate to each parts 0! the resin.

HOWARD K. NASON. 

